Add ß (Latin small letter sharp s) to .de domain IDNA check

The ß was introduced in the [Unicode® Technical Standard #46](http://unicode.org/reports/tr46/#Deviations) standard. According to [denic.de](http://www.denic.de/en/domains/internationalized-domain-names/idn-list.html) this is a valid character.

In the IDNA2003 standard the ß character is not included. This result in a false positive check. IMHO the IDNA2003 will be replaced soon with IDNA2008 and this is a minor side effect.

library/Zend/Validate/Hostname.php

@@ -1043,7 +1043,7 @@ class Zend_Validate_Hostname extends Zend_Validate_Abstract
         'CL'  => array(1 => '/^[\x{002d}0-9a-záéíñóúü]{1,63}$/iu'),
         'CN'  => 'Hostname/Cn.php',
         'COM' => 'Hostname/Com.php',
-        'DE'  => array(1 => '/^[\x{002d}0-9a-zà-öø-ÿăąāćĉčċďđĕěėęēğĝġģĥħĭĩįīıĵķĺľļłńňņŋŏőōœĸŕřŗśŝšşťţŧŭůűũųūŵŷźžż]{1,63}$/iu'),
+        'DE'  => array(1 => '/^[\x{002d}0-9a-zà-öø-ÿăąāćĉčċďđĕěėęēğĝġģĥħĭĩįīıĵķĺľļłńňņŋŏőōœĸŕřŗśŝšşťßţŧŭůűũųūŵŷźžż]{1,63}$/iu'),
         'DK'  => array(1 => '/^[\x{002d}0-9a-zäéöüæøå]{1,63}$/iu'),
         'ES'  => array(1 => '/^[\x{002d}0-9a-zàáçèéíïñòóúü·]{1,63}$/iu'),
         'EU'  => array(1 => '/^[\x{002d}0-9a-zà-öø-ÿ]{1,63}$/iu',